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<pre><span class="sourceLineNo">001</span><a name="line.1"></a>
<span class="sourceLineNo">002</span>/*<a name="line.2"></a>
<span class="sourceLineNo">003</span> * Copyright (C) 2011 Archie L. Cobbs. All rights reserved.<a name="line.3"></a>
<span class="sourceLineNo">004</span> *<a name="line.4"></a>
<span class="sourceLineNo">005</span> * $Id: VaadinUtil.html 906 2014-07-30 00:09:06Z archie.cobbs $<a name="line.5"></a>
<span class="sourceLineNo">006</span> */<a name="line.6"></a>
<span class="sourceLineNo">007</span><a name="line.7"></a>
<span class="sourceLineNo">008</span>package org.dellroad.stuff.vaadin7;<a name="line.8"></a>
<span class="sourceLineNo">009</span><a name="line.9"></a>
<span class="sourceLineNo">010</span>import com.vaadin.server.SessionDestroyEvent;<a name="line.10"></a>
<span class="sourceLineNo">011</span>import com.vaadin.server.SessionDestroyListener;<a name="line.11"></a>
<span class="sourceLineNo">012</span>import com.vaadin.server.VaadinRequest;<a name="line.12"></a>
<span class="sourceLineNo">013</span>import com.vaadin.server.VaadinService;<a name="line.13"></a>
<span class="sourceLineNo">014</span>import com.vaadin.server.VaadinSession;<a name="line.14"></a>
<span class="sourceLineNo">015</span><a name="line.15"></a>
<span class="sourceLineNo">016</span>import java.util.concurrent.Future;<a name="line.16"></a>
<span class="sourceLineNo">017</span><a name="line.17"></a>
<span class="sourceLineNo">018</span>/**<a name="line.18"></a>
<span class="sourceLineNo">019</span> * Miscellaneous utility methods.<a name="line.19"></a>
<span class="sourceLineNo">020</span> */<a name="line.20"></a>
<span class="sourceLineNo">021</span>public final class VaadinUtil {<a name="line.21"></a>
<span class="sourceLineNo">022</span><a name="line.22"></a>
<span class="sourceLineNo">023</span>    private VaadinUtil() {<a name="line.23"></a>
<span class="sourceLineNo">024</span>    }<a name="line.24"></a>
<span class="sourceLineNo">025</span><a name="line.25"></a>
<span class="sourceLineNo">026</span>    /**<a name="line.26"></a>
<span class="sourceLineNo">027</span>     * Verify that we are running in the context of the given session and holding the session's lock.<a name="line.27"></a>
<span class="sourceLineNo">028</span>     * This method can be used by any code that manipulates Vaadin state to assert that the proper Vaadin<a name="line.28"></a>
<span class="sourceLineNo">029</span>     * locking has been performed.<a name="line.29"></a>
<span class="sourceLineNo">030</span>     *<a name="line.30"></a>
<span class="sourceLineNo">031</span>     * @param session session we are supposed to be running with<a name="line.31"></a>
<span class="sourceLineNo">032</span>     * @throws IllegalArgumentException if {@code session} is null<a name="line.32"></a>
<span class="sourceLineNo">033</span>     * @throws IllegalStateException if there is no {@link VaadinSession} associated with the current thread<a name="line.33"></a>
<span class="sourceLineNo">034</span>     * @throws IllegalStateException if the {@link VaadinSession} associated with the current thread is not {@code session}<a name="line.34"></a>
<span class="sourceLineNo">035</span>     * @throws IllegalStateException if the {@link VaadinSession} associated with the current thread is not locked<a name="line.35"></a>
<span class="sourceLineNo">036</span>     * @throws IllegalStateException if the {@link VaadinSession} associated with the current thread is locked by another thread<a name="line.36"></a>
<span class="sourceLineNo">037</span>     */<a name="line.37"></a>
<span class="sourceLineNo">038</span>    public static void assertSession(VaadinSession session) {<a name="line.38"></a>
<span class="sourceLineNo">039</span>        if (session == null)<a name="line.39"></a>
<span class="sourceLineNo">040</span>            throw new IllegalArgumentException("null session");<a name="line.40"></a>
<span class="sourceLineNo">041</span>        final VaadinSession currentSession = VaadinSession.getCurrent();<a name="line.41"></a>
<span class="sourceLineNo">042</span>        if (currentSession == null)<a name="line.42"></a>
<span class="sourceLineNo">043</span>            throw new IllegalStateException("there is no VaadinSession associated with the current thread");<a name="line.43"></a>
<span class="sourceLineNo">044</span>        if (currentSession != session) {<a name="line.44"></a>
<span class="sourceLineNo">045</span>            throw new IllegalStateException("the VaadinSession associated with the current thread " + currentSession<a name="line.45"></a>
<span class="sourceLineNo">046</span>              + " is not the same session as the given one " + session);<a name="line.46"></a>
<span class="sourceLineNo">047</span>        }<a name="line.47"></a>
<span class="sourceLineNo">048</span>        if (!session.hasLock()) {<a name="line.48"></a>
<span class="sourceLineNo">049</span>            throw new IllegalStateException("the VaadinSession associated with the current thread " + currentSession<a name="line.49"></a>
<span class="sourceLineNo">050</span>              + " is not locked by this thread");<a name="line.50"></a>
<span class="sourceLineNo">051</span>        }<a name="line.51"></a>
<span class="sourceLineNo">052</span>    }<a name="line.52"></a>
<span class="sourceLineNo">053</span><a name="line.53"></a>
<span class="sourceLineNo">054</span>    /**<a name="line.54"></a>
<span class="sourceLineNo">055</span>     * Get the {@link VaadinSession} associated with the current thread.<a name="line.55"></a>
<span class="sourceLineNo">056</span>     * This is just a wrapper around {@link VaadinSession#getCurrent} that throws an exception instead<a name="line.56"></a>
<span class="sourceLineNo">057</span>     * of returning null when there is no session associated with the current thread.<a name="line.57"></a>
<span class="sourceLineNo">058</span>     *<a name="line.58"></a>
<span class="sourceLineNo">059</span>     * @return current {@link VaadinSession}, never null<a name="line.59"></a>
<span class="sourceLineNo">060</span>     *<a name="line.60"></a>
<span class="sourceLineNo">061</span>     * @throws IllegalStateException if there is no {@link VaadinSession} associated with the current thread<a name="line.61"></a>
<span class="sourceLineNo">062</span>     */<a name="line.62"></a>
<span class="sourceLineNo">063</span>    public static VaadinSession getCurrentSession() {<a name="line.63"></a>
<span class="sourceLineNo">064</span>        VaadinSession session = VaadinSession.getCurrent();<a name="line.64"></a>
<span class="sourceLineNo">065</span>        if (session == null) {<a name="line.65"></a>
<span class="sourceLineNo">066</span>            throw new IllegalStateException("there is no VaadinSession associated with the current thread;"<a name="line.66"></a>
<span class="sourceLineNo">067</span>              + " are we executing within a Vaadin HTTP request or VaadinUtil.invoke()?");<a name="line.67"></a>
<span class="sourceLineNo">068</span>        }<a name="line.68"></a>
<span class="sourceLineNo">069</span>        return session;<a name="line.69"></a>
<span class="sourceLineNo">070</span>    }<a name="line.70"></a>
<span class="sourceLineNo">071</span><a name="line.71"></a>
<span class="sourceLineNo">072</span>    /**<a name="line.72"></a>
<span class="sourceLineNo">073</span>     * Get the {@link VaadinRequest} associated with the current thread.<a name="line.73"></a>
<span class="sourceLineNo">074</span>     * This is just a wrapper around {@link VaadinService#getCurrentRequest} that throws an exception instead<a name="line.74"></a>
<span class="sourceLineNo">075</span>     * of returning null when there is no request associated with the current thread.<a name="line.75"></a>
<span class="sourceLineNo">076</span>     *<a name="line.76"></a>
<span class="sourceLineNo">077</span>     * @return current {@link VaadinRequest}, never null<a name="line.77"></a>
<span class="sourceLineNo">078</span>     *<a name="line.78"></a>
<span class="sourceLineNo">079</span>     * @throws IllegalStateException if there is no {@link VaadinRequest} associated with the current thread<a name="line.79"></a>
<span class="sourceLineNo">080</span>     */<a name="line.80"></a>
<span class="sourceLineNo">081</span>    public static VaadinRequest getCurrentRequest() {<a name="line.81"></a>
<span class="sourceLineNo">082</span>        VaadinRequest request = VaadinService.getCurrentRequest();<a name="line.82"></a>
<span class="sourceLineNo">083</span>        if (request == null) {<a name="line.83"></a>
<span class="sourceLineNo">084</span>            throw new IllegalStateException("there is no VaadinRequest associated with the current thread;"<a name="line.84"></a>
<span class="sourceLineNo">085</span>              + " are we executing within a Vaadin HTTP request?");<a name="line.85"></a>
<span class="sourceLineNo">086</span>        }<a name="line.86"></a>
<span class="sourceLineNo">087</span>        return request;<a name="line.87"></a>
<span class="sourceLineNo">088</span>    }<a name="line.88"></a>
<span class="sourceLineNo">089</span><a name="line.89"></a>
<span class="sourceLineNo">090</span>    /**<a name="line.90"></a>
<span class="sourceLineNo">091</span>     * Peform some action while holding the given {@link VaadinSession}'s lock.<a name="line.91"></a>
<span class="sourceLineNo">092</span>     *<a name="line.92"></a>
<span class="sourceLineNo">093</span>     * &lt;p&gt;<a name="line.93"></a>
<span class="sourceLineNo">094</span>     * This method now just invokes {@link VaadinSession#accessSynchronously}, a method which didn't exist in earlier<a name="line.94"></a>
<span class="sourceLineNo">095</span>     * versions of Vaadin.<a name="line.95"></a>
<span class="sourceLineNo">096</span>     * &lt;/p&gt;<a name="line.96"></a>
<span class="sourceLineNo">097</span>     *<a name="line.97"></a>
<span class="sourceLineNo">098</span>     * &lt;p&gt;<a name="line.98"></a>
<span class="sourceLineNo">099</span>     * All back-end threads that interact with Vaadin components must use this method (or {@link #invokeLater invokeLater()})<a name="line.99"></a>
<span class="sourceLineNo">100</span>     * to avoid race conditions. Since session locks are re-entrant, it will not cause problems if this method is also<a name="line.100"></a>
<span class="sourceLineNo">101</span>     * used by a "front-end" (i.e., Vaadin HTTP request) thread.<a name="line.101"></a>
<span class="sourceLineNo">102</span>     * &lt;/p&gt;<a name="line.102"></a>
<span class="sourceLineNo">103</span>     *<a name="line.103"></a>
<span class="sourceLineNo">104</span>     * &lt;p&gt;<a name="line.104"></a>
<span class="sourceLineNo">105</span>     * Note: when executing within a Vaadin HTTP request, the current thread's {@link VaadinSession} is available<a name="line.105"></a>
<span class="sourceLineNo">106</span>     * via {@link VaadinSession#getCurrent}; consider also using {@link VaadinApplication#invoke} instead of this method.<a name="line.106"></a>
<span class="sourceLineNo">107</span>     * &lt;/p&gt;<a name="line.107"></a>
<span class="sourceLineNo">108</span>     *<a name="line.108"></a>
<span class="sourceLineNo">109</span>     * &lt;p&gt;<a name="line.109"></a>
<span class="sourceLineNo">110</span>     * &lt;b&gt;Warning:&lt;/b&gt; background threads should be careful when invoking this method to ensure they<a name="line.110"></a>
<span class="sourceLineNo">111</span>     * are not already holding an application-specific lock that a separate HTTP request thread could<a name="line.111"></a>
<span class="sourceLineNo">112</span>     * attempt to acquire during its normal processing: because the HTTP request thread will probably<a name="line.112"></a>
<span class="sourceLineNo">113</span>     * already be holding the session lock when it attempts to acquire the application-specific lock,<a name="line.113"></a>
<span class="sourceLineNo">114</span>     * this creates the potential for a lock-ordering reversal deadlock.<a name="line.114"></a>
<span class="sourceLineNo">115</span>     * &lt;/p&gt;<a name="line.115"></a>
<span class="sourceLineNo">116</span>     *<a name="line.116"></a>
<span class="sourceLineNo">117</span>     * @throws IllegalArgumentException if either parameter is null<a name="line.117"></a>
<span class="sourceLineNo">118</span>     * @see VaadinApplication#invoke<a name="line.118"></a>
<span class="sourceLineNo">119</span>     */<a name="line.119"></a>
<span class="sourceLineNo">120</span>    public static void invoke(VaadinSession session, Runnable action) {<a name="line.120"></a>
<span class="sourceLineNo">121</span>        if (session == null)<a name="line.121"></a>
<span class="sourceLineNo">122</span>            throw new IllegalArgumentException("null session");<a name="line.122"></a>
<span class="sourceLineNo">123</span>        if (action == null)<a name="line.123"></a>
<span class="sourceLineNo">124</span>            throw new IllegalArgumentException("null action");<a name="line.124"></a>
<span class="sourceLineNo">125</span>        session.accessSynchronously(action);<a name="line.125"></a>
<span class="sourceLineNo">126</span>    }<a name="line.126"></a>
<span class="sourceLineNo">127</span><a name="line.127"></a>
<span class="sourceLineNo">128</span>    /**<a name="line.128"></a>
<span class="sourceLineNo">129</span>     * Peform some action while holding the given {@link VaadinSession}'s lock, but do so asynchronously.<a name="line.129"></a>
<span class="sourceLineNo">130</span>     *<a name="line.130"></a>
<span class="sourceLineNo">131</span>     * &lt;p&gt;<a name="line.131"></a>
<span class="sourceLineNo">132</span>     * Here the term "asynchronously" means:<a name="line.132"></a>
<span class="sourceLineNo">133</span>     * &lt;ul&gt;<a name="line.133"></a>
<span class="sourceLineNo">134</span>     *  &lt;li&gt;If any thread holds the session lock (including the current thread), this method will return<a name="line.134"></a>
<span class="sourceLineNo">135</span>     *      immediately and the action will be performed later, when the session is eventually unlocked.&lt;/li&gt;<a name="line.135"></a>
<span class="sourceLineNo">136</span>     *  &lt;li&gt;If no thread holds the session lock, the session will be locked and the action performed<a name="line.136"></a>
<span class="sourceLineNo">137</span>     *      synchronously by the current thread.&lt;/li&gt;<a name="line.137"></a>
<span class="sourceLineNo">138</span>     * &lt;/ul&gt;<a name="line.138"></a>
<span class="sourceLineNo">139</span>     * &lt;/p&gt;<a name="line.139"></a>
<span class="sourceLineNo">140</span>     *<a name="line.140"></a>
<span class="sourceLineNo">141</span>     * &lt;p&gt;<a name="line.141"></a>
<span class="sourceLineNo">142</span>     * This method now just invokes {@link VaadinSession#access}, a method which didn't exist in earlier<a name="line.142"></a>
<span class="sourceLineNo">143</span>     * versions of Vaadin.<a name="line.143"></a>
<span class="sourceLineNo">144</span>     * &lt;/p&gt;<a name="line.144"></a>
<span class="sourceLineNo">145</span>     *<a name="line.145"></a>
<span class="sourceLineNo">146</span>     * &lt;p&gt;<a name="line.146"></a>
<span class="sourceLineNo">147</span>     * Note: when executing within a Vaadin HTTP request, the current thread's {@link VaadinSession} is available<a name="line.147"></a>
<span class="sourceLineNo">148</span>     * via {@link VaadinSession#getCurrent}; consider also using {@link VaadinApplication#invokeLater} instead of this method.<a name="line.148"></a>
<span class="sourceLineNo">149</span>     * &lt;/p&gt;<a name="line.149"></a>
<span class="sourceLineNo">150</span>     *<a name="line.150"></a>
<span class="sourceLineNo">151</span>     * @return a corresponding {@link Future}<a name="line.151"></a>
<span class="sourceLineNo">152</span>     * @throws IllegalArgumentException if either parameter is null<a name="line.152"></a>
<span class="sourceLineNo">153</span>     * @see #invoke<a name="line.153"></a>
<span class="sourceLineNo">154</span>     * @see VaadinApplication#invokeLater<a name="line.154"></a>
<span class="sourceLineNo">155</span>     */<a name="line.155"></a>
<span class="sourceLineNo">156</span>    public static Future&lt;Void&gt; invokeLater(VaadinSession session, Runnable action) {<a name="line.156"></a>
<span class="sourceLineNo">157</span>        if (session == null)<a name="line.157"></a>
<span class="sourceLineNo">158</span>            throw new IllegalArgumentException("null session");<a name="line.158"></a>
<span class="sourceLineNo">159</span>        if (action == null)<a name="line.159"></a>
<span class="sourceLineNo">160</span>            throw new IllegalArgumentException("null action");<a name="line.160"></a>
<span class="sourceLineNo">161</span>        return session.access(action);<a name="line.161"></a>
<span class="sourceLineNo">162</span>    }<a name="line.162"></a>
<span class="sourceLineNo">163</span><a name="line.163"></a>
<span class="sourceLineNo">164</span>    /**<a name="line.164"></a>
<span class="sourceLineNo">165</span>     * Register for a notification when the {@link VaadinSession} is closed, without creating a memory leak.<a name="line.165"></a>
<span class="sourceLineNo">166</span>     * This method is intended to be used by listeners that are themselves part of a Vaadin application.<a name="line.166"></a>
<span class="sourceLineNo">167</span>     *<a name="line.167"></a>
<span class="sourceLineNo">168</span>     * &lt;p&gt;<a name="line.168"></a>
<span class="sourceLineNo">169</span>     * Explanation: the {@link VaadinSession} class does not provide a listener API directly; instead, you must<a name="line.169"></a>
<span class="sourceLineNo">170</span>     * use the {@link com.vaadin.server.VaadinService} class. However, registering as a listener on the<a name="line.170"></a>
<span class="sourceLineNo">171</span>     * {@link com.vaadin.server.VaadinService} when you are part of a Vaadin application sets you up for a memory leak<a name="line.171"></a>
<span class="sourceLineNo">172</span>     * if you forget to unregister yourself when the notification arrives, because the {@link com.vaadin.server.VaadinService}<a name="line.172"></a>
<span class="sourceLineNo">173</span>     * lifetime is longer than the {@link VaadinSession} lifetime. This method handles that de-registration for<a name="line.173"></a>
<span class="sourceLineNo">174</span>     * you automatically.<a name="line.174"></a>
<span class="sourceLineNo">175</span>     *<a name="line.175"></a>
<span class="sourceLineNo">176</span>     * @throws IllegalArgumentException if either parameter is null<a name="line.176"></a>
<span class="sourceLineNo">177</span>     * @see VaadinApplication#addSessionDestroyListener<a name="line.177"></a>
<span class="sourceLineNo">178</span>     */<a name="line.178"></a>
<span class="sourceLineNo">179</span>    public static void addSessionDestroyListener(VaadinSession session, SessionDestroyListener listener) {<a name="line.179"></a>
<span class="sourceLineNo">180</span>        session.getService().addSessionDestroyListener(new LeakAvoidingDestroyListener(session, listener));<a name="line.180"></a>
<span class="sourceLineNo">181</span>    }<a name="line.181"></a>
<span class="sourceLineNo">182</span><a name="line.182"></a>
<span class="sourceLineNo">183</span>    /**<a name="line.183"></a>
<span class="sourceLineNo">184</span>     * Remove a listener added via {@link #addSessionDestroyListener addSessionDestroyListener()}.<a name="line.184"></a>
<span class="sourceLineNo">185</span>     *<a name="line.185"></a>
<span class="sourceLineNo">186</span>     * @throws IllegalArgumentException if either parameter is null<a name="line.186"></a>
<span class="sourceLineNo">187</span>     * @see VaadinApplication#removeSessionDestroyListener<a name="line.187"></a>
<span class="sourceLineNo">188</span>     */<a name="line.188"></a>
<span class="sourceLineNo">189</span>    public static void removeSessionDestroyListener(VaadinSession session, SessionDestroyListener listener) {<a name="line.189"></a>
<span class="sourceLineNo">190</span>        session.getService().removeSessionDestroyListener(new LeakAvoidingDestroyListener(session, listener));<a name="line.190"></a>
<span class="sourceLineNo">191</span>    }<a name="line.191"></a>
<span class="sourceLineNo">192</span><a name="line.192"></a>
<span class="sourceLineNo">193</span>// LeakAvoidingDestroyListener<a name="line.193"></a>
<span class="sourceLineNo">194</span><a name="line.194"></a>
<span class="sourceLineNo">195</span>    @SuppressWarnings("serial")<a name="line.195"></a>
<span class="sourceLineNo">196</span>    private static class LeakAvoidingDestroyListener implements SessionDestroyListener {<a name="line.196"></a>
<span class="sourceLineNo">197</span><a name="line.197"></a>
<span class="sourceLineNo">198</span>        private final VaadinSession session;<a name="line.198"></a>
<span class="sourceLineNo">199</span>        private final SessionDestroyListener listener;<a name="line.199"></a>
<span class="sourceLineNo">200</span><a name="line.200"></a>
<span class="sourceLineNo">201</span>        public LeakAvoidingDestroyListener(VaadinSession session, SessionDestroyListener listener) {<a name="line.201"></a>
<span class="sourceLineNo">202</span>            if (session == null)<a name="line.202"></a>
<span class="sourceLineNo">203</span>                throw new IllegalArgumentException("null session");<a name="line.203"></a>
<span class="sourceLineNo">204</span>            if (listener == null)<a name="line.204"></a>
<span class="sourceLineNo">205</span>                throw new IllegalArgumentException("null listener");<a name="line.205"></a>
<span class="sourceLineNo">206</span>            this.session = session;<a name="line.206"></a>
<span class="sourceLineNo">207</span>            this.listener = listener;<a name="line.207"></a>
<span class="sourceLineNo">208</span>        }<a name="line.208"></a>
<span class="sourceLineNo">209</span><a name="line.209"></a>
<span class="sourceLineNo">210</span>        @Override<a name="line.210"></a>
<span class="sourceLineNo">211</span>        public void sessionDestroy(SessionDestroyEvent event) {<a name="line.211"></a>
<span class="sourceLineNo">212</span>            final VaadinSession closedSession = event.getSession();<a name="line.212"></a>
<span class="sourceLineNo">213</span>            if (closedSession == this.session) {<a name="line.213"></a>
<span class="sourceLineNo">214</span>                this.session.getService().removeSessionDestroyListener(this);       // remove myself as listener to avoid mem leak<a name="line.214"></a>
<span class="sourceLineNo">215</span>                this.listener.sessionDestroy(event);<a name="line.215"></a>
<span class="sourceLineNo">216</span>            }<a name="line.216"></a>
<span class="sourceLineNo">217</span>        }<a name="line.217"></a>
<span class="sourceLineNo">218</span><a name="line.218"></a>
<span class="sourceLineNo">219</span>        @Override<a name="line.219"></a>
<span class="sourceLineNo">220</span>        public boolean equals(Object obj) {<a name="line.220"></a>
<span class="sourceLineNo">221</span>            if (obj == null || obj.getClass() != this.getClass())<a name="line.221"></a>
<span class="sourceLineNo">222</span>                return false;<a name="line.222"></a>
<span class="sourceLineNo">223</span>            LeakAvoidingDestroyListener that = (LeakAvoidingDestroyListener)obj;<a name="line.223"></a>
<span class="sourceLineNo">224</span>            return this.session == that.session &amp;&amp; this.listener.equals(that.listener);<a name="line.224"></a>
<span class="sourceLineNo">225</span>        }<a name="line.225"></a>
<span class="sourceLineNo">226</span><a name="line.226"></a>
<span class="sourceLineNo">227</span>        @Override<a name="line.227"></a>
<span class="sourceLineNo">228</span>        public int hashCode() {<a name="line.228"></a>
<span class="sourceLineNo">229</span>            return this.session.hashCode() ^ this.listener.hashCode();<a name="line.229"></a>
<span class="sourceLineNo">230</span>        }<a name="line.230"></a>
<span class="sourceLineNo">231</span>    }<a name="line.231"></a>
<span class="sourceLineNo">232</span>}<a name="line.232"></a>
<span class="sourceLineNo">233</span><a name="line.233"></a>




























































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